COMPARISON OF T-2(ASTERISK)-WEIGHTED SEQUENCES FOR FUNCTIONAL MRI

Several sequences, including conventional gradient-echo sequence (e.g. , FLASH), gradient-echo echo-planar imaging (EPI), T-2 prepared ultra fast gradient echo technique (TurboFLASH), and T-2-weighted spiral se quence, are currently used for T-2-weighted functional magnetic reson ance imaging. This paper presents a comparison of FLASH, gradient-echo EPI, and T-2-prepared TurboFLASH. Experimental results have demonstr ated that these sequences have different susceptibility to physiologic fluctuation, which is likely the dominant source of noise. EPI images exhibit the lowest relative fluctuation, while images obtained by FLA SH and TurboFLASH, respectively, display similar relative fluctuation. Functional maps generated using these sequences are comparable but ex hibit different sensitivity to activation from large vessels. Conseque ntly, interpretation of activation results from various maps should ta ke into account the difference in the sequences. (C) 1995 John Wiley & Sons, Inc.